I was told in one of my previous threads that all of that carbon based nonsense for your filters was not necessary and it was perfectly fine to use regular sponges stuffed down into your filter. I picke dup some of these sponges from walmart today and am wondering if I can use them in my filter with out any harm done to my tank or fish.

I'm always right. I'm in a position where I have secret information that I know this to be true.

My filter only has one spongy pad in it, and it's maybe .25" thick. But, it also has a fabric cartridge behind it which may or may not serve a purpose other than simply containing carbon. (I only have that in there because I bought a box of cartridge replacements; for shame, I know.)